Bacterial vaginosis (BV) was previously called nonspecific vaginitis or Gardnerella-associated vaginitis. Symptomatic women report an offensive, fishy-smelling discharge, which is most marked after unprotected intercourse or at the time of menstruation. It is unknown how BPDE promotes the induction of prophages in lysogenic lactobacilli. The study of the Escherichia coli lambda phage, however, may shed some light on this question. The number of vaginal lactobacilli can be reduced in a smoking woman: by inducing the lysogenic strains to lyse and release phages or when the released phages may in turn lyse other strains by infection. The relationship between smoking and BV may be much more complicated, since smoking can weaken the human immune system and also cause many other health problems. The author and coworkers have documented that phages infect vaginal lactobacilli under in vitro conditions. This suggests that phage infection may occur in vivo as well. DNA evidence of phages were sought in different vaginal lactobacilli that would suggest an infection and/or transmission of phages in women and evidence that phages are released from the male urinary tract. The major difference is that lysogenic bacteria are capable of releasing phages, either spontaneously or upon induction, such as by cigarette chemicals. Collectively, this study provides initial evidence that vaginal Lactobacillus phages can be transmissible infective agents. In summary, some vaginal and yogurt lactobacilli are lysogens that spontaneously release phages. Future studies should include establishing phage taxonomy, characterizing phage diversity, determining phage genomic sequences, and studying interactions between phages and lactobacilli.

Comparison of maximal phage release frequencies among spontaneous, BPDE, and mitomycin C inductions. The concentration of mitomycin C was constant, at 200 g/ml.The concentrations of BPDE for maximal phage release were 1 to 2 µg/ml for ϕkc5a, 16 ng/ml for ϕkc7a, and 6 µg/ml for ϕy8.

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FIGURE 7

Comparison of maximal phage release frequencies among spontaneous, BPDE, and mitomycin C inductions. The concentration of mitomycin C was constant, at 200 g/ml.The concentrations of BPDE for maximal phage release were 1 to 2 µg/ml for ϕkc5a, 16 ng/ml for ϕkc7a, and 6 µg/ml for ϕy8.

In vitro BV model. (A) Without phage, L. jensenii KC13 remained dominant throughout the 12-h growth period in the Lactobacillus-G. vaginalis coculture system. (B) After the addition of phage ϕkc39, the bacterial dominance shifted from Lactobacillus to G. vaginalis.

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FIGURE 9

In vitro BV model. (A) Without phage, L. jensenii KC13 remained dominant throughout the 12-h growth period in the Lactobacillus-G. vaginalis coculture system. (B) After the addition of phage ϕkc39, the bacterial dominance shifted from Lactobacillus to G. vaginalis.

5.Antonio, M.A.,, S. E.Hawes,, and S. L.Hillier. 1999. The identification of vaginal Lactobacillus species and the demographic and microbiologic characteristics of women colonized by these species. J. Infect. Dis. 180:1950–1956.

aFor determinations of phage sequence data for PCR analysis, genomic DNAs of four phages, representing each morphotype, were digested with Sau3A1.The DNA fragments were cloned into pUC18.A plasmid that carried an insert of about 1 kb was selected for each phage.The sequence was determined by the automated sequencing facility at the University of Missouri, Kansas City.

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TABLE 3

aFor determinations of phage sequence data for PCR analysis, genomic DNAs of four phages, representing each morphotype, were digested with Sau3A1.The DNA fragments were cloned into pUC18.A plasmid that carried an insert of about 1 kb was selected for each phage.The sequence was determined by the automated sequencing facility at the University of Missouri, Kansas City.

aAmong the 20 yogurt products tested, 11 were found to release phages, of which 7 infected vaginal lactobacilli under in vitro conditions. For the protection of the reputations of these commercial products, however, the sources of these phages are not specifically indicated.

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TABLE 4

Commercial Lactobacillus products analyzed for phages

aAmong the 20 yogurt products tested, 11 were found to release phages, of which 7 infected vaginal lactobacilli under in vitro conditions. For the protection of the reputations of these commercial products, however, the sources of these phages are not specifically indicated.